Despite the success of modern cancer chemotherapy in selected tumors, half of all cancer patients either fail to respond or will relapse during their follow-up period and die from metastatic disease. The hope for improved treatment outcome for patients with metastatic disease resides in intensive research to optimize the administration of the currently available and new agents and to combine them in the most appropriate way. Topotecan has a proven antitumor effect in metastatic cancer. ZD0473 is a new agent with significant antitumor activity in vitro but insufficient data available in humans. The aim of this trial is to combine these two drugs. The goal of this Phase I trial is to determine the maximum tolerated dose of ZD0473 and Topotecan when used in combination. Due to the toxicity of cytolytics that is very close to the therapeutic index, Phase I trials can only be carried out in cancer patients. Patients included in this Phase I trial will have solid tumors.